Two different kinds of conventional chemical dispensing systems are used to clean wafers. A conventional chemical dispensing system may include a single nozzle and a movable arm. The single nozzle is mounted onto the movable arm. In operation, the single nozzle can previously dispense a chemical fluid at a home position away from a stage to prevent the aging effect of the chemical fluid. Thereafter, the single nozzle moves with the movable arm above a wafer supported by the stage, and dispenses the chemical fluid onto the wafer for cleaning.
However, when the single nozzle previously dispenses the chemical fluid, the pre-dispensed chemical fluid may pollute the movable arm. Since the conventional chemical dispensing system only has the single nozzle, it is difficult to evenly dispense the chemical fluid on the wafer, and the particles on the wafer cannot be cleaned uniformly. Moreover, the nozzle does not have self-clean functions, such that the chemical dispensing system needs to be stopped for cleaning the nozzle. As a result, the production capacity and the yield rate of the wafer are difficult to be improved.
Another conventional chemical dispensing system may include a dispensing bar above a stage and a dispensing head. The dispensing bar is connected the dispensing head. When the dispensing bar previously dispenses the chemical fluid to prevent the aging effect of the chemical fluid, the chemical fluid may be poured onto the chuck and then damage the chuck and the motor of the stage. If the dispensing bar does not previously dispense the chemical fluid, the aging effect of the chemical fluid may cause particle issues and etching rate drift in following process steps. Therefore, a dummy wafer for protecting the stage is required, but the productivity of the chemical dispensing system is reduced.
Moreover, the dispensing bar does not have self-clean functions, such that the chemical dispensing system needs to be stopped for cleaning the dispensing bar. As a result, the production capacity and the yield rate of the wafer are difficult to be improved.